In recent years, authentication systems for mobile electronic devices using handwriting traces have been disclosed. For example, the screen of a display unit of a mobile electronic device is lighted down when a screen lighting-down operation of the display unit is detected or when the duration of non-operating time continues for a time period equal to or greater than a predetermined time period.
For example, if the duration of non-operating time has continued for a time period equal to or greater than a predetermined time period while an application screen is screen-displayed on the display unit of a mobile electronic device, the screen of the display unit is lighted down. Afterward, when the screen of the display unit of the mobile electronic device is lighted up again and, when a user's recovery operation for displaying the application screen again is detected, an authentication screen is displayed on the screen in an operation-locked state where information referencing and operation reception via the application screen are not allowed. Accordingly, as the mobile electronic device shifts to the operation-locked state, user's incorrect operations on the mobile electronic device or unauthorized operations by a third party can be prevented.
Furthermore, in the mobile electronic device, if a user is authenticated in response to an authentication operation on the authentication screen, the operation-locked state is canceled and the application screen is displayed again. As a result, information referencing and operation reception on the application screen of the mobile electronic device are allowed for the user. Japanese Laid-open Patent Publication No. 2010-266997
In mobile electronic devices, however, if the duration of non-operating time has continued for a time period equal to or greater than a predetermined time period, for example, when the application screen of a map application is displayed, the display unit is lighted down and then the authentication screen is displayed in response to a user's recovery operation. After the screen of the display unit is lighted down, the application screen is displayed again so that the application screen can be continuously used; however, every time this happens, the user of the mobile electronic device needs to perform an authentication operation on the authentication screen, i.e., perform an operation for canceling the operation-locked state.